System of coding and decoding



April 4, 1939. w. s. LEMMON ET AL SYSTEM OF CODING AND DECODING Filed Sept.

Patented Aipr.4 ,1939

PATENT OFFICE SYSTEM or copme AND nnconmc Walter S. Lemmon, New York, Clyde J. Fitch, Endlcott, and Richard F. Walz, New York, N. Y., assignors to International Business Machines Corporation, New York, N. Y., a corporation of New York Application September 5, 1935 Serial No. 39,294

9 Claims.

This invention relates to the art of secret writing and more particularly to a new system for transforminglanguage messages into decodable secret code.

An object of the present invention is to provide an improved system for the more rapid and accurate coding and decoding of characters or signs used in variouscommunications.

Another object of the invention is to prevent lo periodical recurrences by causing irregularities in the coding process by a new system so as to introduce a new order of complexity of code according to an arbitrary system.

A further object of the invention is to produce a resultant which ismost complex but whereby the coding-and decoding operations are simplified.

Heretofore, in order to prevent periodical recurrences in forming unintelligible sequences of characters in a coded message and toinsure a continuous. variation and transposition of the resultant character form, the electrical systems pro ducing such efiects, at present, employ a plurality or multiplicity of coding drums orwheels which are adapted to be actuated diiierentially w to alter the circuit connections of the system. It has been found that systems of this type are .apt to become quite complicated and tend to reduce the overall rate of speed of operation of the system.

In contradistinction to the present systems, the

drum or wheel, acting as a circuit connection changing device to which, at variable times, a definite movement is imparted to alter, at irregular intervals, the circuit connections of the system. For the purpose of obtaining operation at irregular intervals of thecode wheel an electrical circuit arrangement of varying pattem'is employed which shifts the codingcircuits aperiodically. I m More specifically, for illustrative purposes a plurality of well known distributing orrotary switches are used, the contacts of which are connected in an arbitrary manner to provide innumerable cycles of operation thereof without incurring or repeating a similar circuit pattern or arrangement.

' A further feature of the present invention is the provision of simple and automatic means of restoring the controlling circuit arrangements and the coding circuits to the normal starting position. g

Further and other objects and advantages will be hereinafter set forth in the accompanying specification and claims, and shown in the drawinvention to be disclosed embodies a single coding ing, which by way of illustration shows what is now considered to be the preferred embodiment of the invention;

In the drawing'the circuits are shown embodying one preferred form of the present invention. Referring to the drawing, a well known form of coding drum or wheel arrangement is shown diagrammatically and generally indicated by the reference character l0. Two groups of contacts ll and I2 are shown to engage a multi-segment drum or commutator ringv l3 partly developed. The group of contacts I! are arranged to engage permanently the associated segments l3--a,

whereas the group of contacts l2 are adapted to be positioned with respect to the drum segments l3-a at irregular intervals uponenergization and release of the associated electromagnet R5. It is deemed unnecessary to describe the code drum further in detail, since a complete description and disclosure of the code drum is set forth in a copending application .Serial No; 730,905 filed June 16, 1934, and wherein the electromagnet R-5 is designated I55 and adapted to position the contacts 39, corresponding to. the said contacts l2 in the present disclosure, with resp ct to the commutator ring 4! (corresponding to\ the ring l3 in the present drawing) and contacts. 42 corresponding to present contacts I]. i

Controlling instrumentalities, such as key bars [4 are connected to the contacts ll, so that upon depression of an individual character key the associated contacts l5 connect grounded battery l6 v to the corresponding contact II and associated segment l3a to energize the connected circuit through the corresponding contact l2 engaging the same said segment i3--a, and the control element embodied therein, for example, thesolenoid ll, effecting depression of a controlling key bar l8 and recording the selected code character.

The controlling instrumentalities M and It may comprise the key bars of a typewriter or punch to record the coded character. It is obvious that the remaining character keys of a standard typewriter. one form of which is described in the above mentioned application, may be connected to additional segments I3-a in the manner shown in the simplified accompanying diagram.

The preferred form of the invention at present' is adapted to energize the magnet R5 at irregular intervals causing a displacement of the brushes [2 andwill now be described. a

A plurality of distributing or rotary switches 2| to 24 inclusive are provided to form and complete various electrical circuit patterns to control the energization of magnet R! in such a manner as to prevent periodical recurrences of the same electrical pattern. It will become obvious as the description progresses that additional distributing switches can be provided to further complicate the resultant circuit pattern without departing from the broad scope of the present invention.

The distributing switches 2! to 24 inclusive are a well known standard type of rotary switches and are similar in design to the selector switches used in telephonic systems and comprise in general shafts 2ls to 24-4, electromagnets R-l to R-4 .for rotating the associated shafts one step at a time, a plurality of brushes 2m to 0, 22a to 0, etc., insulatively mounted upon the associated shafts, and arcuate banks of stationary contacts 2l-ca to co, 22ca to co, etc. adapted for cooperation with said brushes. In the specific embodiment the arcuate banks are shown to have twenty-five stationary contacts however this number of contacts can be increased or decreased as seen fit for the particular application.

It is to be noted that the two banks of arcuate contacts of each switch are connected similarly and function only when the homing circuits are energized to position the switch brushes to the home or normal position as shown in the drawing. These circuits will be described hereinafter.

The electromagnet R-i associated with the switch 2lis adapted to be energized upon the depression of each character key of the controlling typewriter or keyboard Tl upon which the intelligible sequence of characters are selected to be coded by another device T2 which may be a typewriter similar to Ti.

Contacts 25 are provided for this purpose and are closed upon the depression of each character key Id of the typewriter Tl. Specific mechanism for this provision is not shown since it is old and well known in the art; one method, which has been used heretofore, is to provide a common bar beneath the key bars of the typewriter and arranged so that the depression of the character keys lowers the common bar which in turn causes the common contacts to be closed.

Closureof contacts 25 connect grounded battery 26 to the electromagnet RI, energizing the magnet to effect rotation of the brush shaft 2 ls to step the brushes 2la to c ahead to engage the next adjacent contacts in the associated arcu ate banks.

It is well to state here that the third bank of contacts 2l-cc to 23-00 of switches 2! to 23 and the contacts 24-00 to 2Q-ce in the banks of switch 24 and the associated circuits therewith form the control circuits to irregularlyand arbitrarily energize the magnet R- and position the contacts l2 thereby altering the circuit connections between the units Tl and T2 effecting a change in the sequence of the recorded characters accordingly. The arcuate banks of contacts forming the control means for magnet R-5 are shown to be connected to form one particu lar form of circuit pattern, for example, the contacts 2lcc of switch- 2| are connected so that upon every fifth character selected the contacts 'in they-said bank are live, however, it is obof the disclosure are merely one illustrative set of connections possible to be embodied in the present invention.

The contacts 2l-cc are connected by a common conductor 21 to the brush 24d of dis-- conductors 28 and 23 respectively, the purpose of which will be understood presently.

From the description set forth, thus far, it is understood that upon depression of any character key I4, contacts 25 are closed to permit battery 26 to energize magnet Rl Brushes 2'Ia to c are stepped ahead each time the magnet is operated to engage the associated contacts 2 Ica to cc. Engagement of the connected contacts 2l-cc permits .current to flow from grounded battery 30, brush 2l-c, conductor 21, brush 24d, connected contacts 24--cd, and/either to conductor 28 or 29 to energize magnet R2 and relay RL2 or magnet R-3 and relay RL3, respectively, depending upon the position of brush 24d. From the brush position shown in the drawing the magnet R-2' and Relay RL2 would be energized. Energization and release of magnet R--2 causes the associated brushes 22a to c to be stepped ahead to engage the adjacent contacts 22ca to cc.

Energization of relay RL2 opens the assoelate contacts 3! disconnecting magnet R-2 from conductor 28. Relay RL2 remains energized so long as battery 30 is connected to the particular and associated con-tact 24-013, preventing further energization of magnet R-2.

Assume now that operation of the said magnet R2 advanced the brushes 22--a to c from the contacts 22ca to cc shown to be engaged in the drawing to the corresponding adjacent contacts. Referring now to the third bank of contacts 22-cc grounded battery 30 is connected by brush 22-c, to the engaged contact 22ca, common conductor 32 to contacts 26--cc of switch 23 (third arcuate bank of contacts) brush 24c, conductor 33 to relay RL5 and by the conductor 34 to magnet R5. It was mentioned hereinbefore that upon energmation and release of magnet R--5, the group of contacts or brushes l2 associated with the disk-segments l3-a are advanced or positioned so as to alter the circuit connections'between typewriters Tl and T2.

It is well to mention at'this time, but the purpose thereof to be completely described hereinafter, that brush 35 is also adapted to be advanced one step each time magnet R5 is operated to engage the adjacent contact 36. The shaft 31 of the brush 35 corresponds to shaft 37 of the aforementioned application; so that it is obvious each time the shaft 31 is rotated a step upon operation of magnet R.5 both the group of brushes l2 and brush 35 are advanced, and in view of the complete description in the said application, this brief description is sufiicient.

Energization of relay RLS operates the associated and normally closed contacts 38 to dis-' I engages a connected contact the conductor 21 and connected brush 24-11 are energized and so long as the first contact 24-011 of the arcuate bank is; engaged by the associated brush relay- RL-Z and magnet R,2 are energized. Energization of relay RL2 opens the associated contact 3| deenergizing magnet R-2 and brushes 22-0. to c are advanced one step. Obviously,

when the advancedbrush 22c engages a connected contact relay RIP-5 and magnet R-5 are energizedeither through conductor 32 or conductor 39. During the completion nF the fifth cycle of brush 2 [-0, magnet Rr-2 will be operated to step the brushes 22--a to c to the twenty fifth contacts of the arcuate banks, so that battery 30 is connected now by the brush 22-0, conductor 40, contact 24ce, brush 24e and conductor 4| to energize relay R.L4 and magnet 3-4. Opera ation, of magnet Rr-4 now steps its brushes ahead one contact. Relay RIP- 4 remains energized to disconnect magnet R--4 frornconductor 4! for the same purpose as explained with respect to relays RIP-2 and RIF-3, namely to prevent the 3-4 magnet from further eriergization.

Upon completion of another cycle brush 22-0 again connects battery 30 to the same circuit just described to energize magnet R-4 and the associated relay RL4, thereby advancing the asso-,

ciated brushes to the third contacts of the arcuate ba Wher upon, further engagement of the connected contacts 2l-cc by brush fl e, battery 30 is connected to conductor 21, brush 24-11, third contact 24-011, conductor 29 to energize magnet R3 and the associated relay RL-3, thereby advancing brushes 23a to c.

Upon the completion of a cycle of the brushes of switch 23, battery 30 is connected by brush 23-c, to conductor 42, third contact 24ce, brush 24e and conductor 4!, energizing magnet R-4 and advancing the associated brushes one step. 7

Without further detailed des'cription of the said circuits it is evident that upon completion of a number of cycles by brush 2l--c, brush 22-0 is advanced to energize at irregular intervals magnet R. -5 and alter the circuit connections between units Tl and T2.

- Similarly, upon complete cycles of operation of brush 22c, magnet R-4 is energized to alter the circuit pattern. by connecting switch 23 in the magnet R-5 controlling circuit. And upon completion of a number of cycles of brushes 23-11 to c, operation of magnet R-4 causes switch 22 to be inserted in the said control circuit for magnet R5. It is self-evident from the description inst set forth, that additional switches similar to switches 2| to 24 inclusive may be added to increase the number of permuis to select the sequence of unintelligible characters by the keys l4 of unit T--| and record the intelligible sequence of characters on unit T-2, it .is necessary before decqding to have the circuit changing devices all in the same normal or home position that the units occupied before coding the message. Provision has been made to reset automatically all the units, such as brushes 2l-ato c, 22-a to 0, etc. and contacts 12 and brush 35, to the normal home position, namely, the position of the said units as indicated in the drawing, and will not be described.

Depression of the homing key 45 momentarily connects grounded battery 46 to relay 41, energizing the relay to operate the associated contacts 48, 49 and 61. Letit be assumed that upon the completion of coding the message all the displaceable units, namely brushes 2 l-a to 0, etc. and contacts 12 and brush 35, have been po sitioned so that each unit is displaced from the normal positionas indicated in the drawing.

Therefore, operation of contacts 48 permits grounded battery 50 through any connected contact 2l-cb, brush 2I--b, and conductor 5! to locking circuitarrangement for the said relay. In conjunction with relay 41, it should be mentioned here, that the relay is a slow release relay, so that the associated contact 48 remains closed or operated for a timed interval equivalent to the time necessary for the brush 2l-b to be ad-l vanced to an adjacent associated contact.

Operation of contacts 49 connects the grounded battery 46, by conductor 52, brush 2I-a and associated contact 2i-ca through normally closed contacts to magnet R-l, energizing the magnet to advance the brushes 2I-a to c. Advancement of the brushes, irrespective of the position of brushes 22--a, 23-4, etc. will not open the lock circuit through contact 48 due'to the slow release energized successively, and individually in a simi-- lar manner to reset the associated brushes, respectively, to normal. The brushes of the sec ond bank of each of theswitches and the associated connected contacts act, as explained before, as. the holding circuit for relay 41.

Thereforefit is evident upon the completion of resetting all the brushes 2l--b, 22b, 23--b and 24--b to the normal position, (namely, the first contact of the respective arcuate bank of contacts) battery 5|] is disconnected from all the said brushes, thereby preventing further energization of relay 41 through the associated contact 48, and thus restoring relay 41 to the normal position shown in the drawing.

The said momentary depression of key 45 also permits the grounded battery 46 to energize relay 55, to operate the associated contacts 56, 51 and .66. Operation of contacts 56 connects grounded battery through the contacts 59 (which are closed at all times when the contacts l2 and brush 35 :are not in the normal home position) andconductor 60 to maintain relay 55 energized and acts as a locking circuit for said' relay. Grounded battery. is thenconnected through closed contacts 51, conductor GI, and normally closed contacts 62 to energize magnet R 5.

Through the operation of the interrupting contacts 62 magnet R-5 is energized successively to continue to energize relay 41 and thus acts as a 5. indicates the-normal position, and the brush 35 upon. engaging the said contact "36 completes a circuit fromgrounded battery 58 to energize relay 85 operating contacts 59 to openthe locking circuit for relay 55, thereby disconnecting battery 48 from the said circuits just traced.- Relay 65 is a fast operating relay and breaks 'the contacts 59 to camse'deenergization of relay 55 before the magnet R5 can be energized, therefore once the contacts l2 and brush 35- have been reset to home position, further actuation of the said contacts and brush by subsequent energization oi. magnet R5 cannot be eifected to cause a faulty positioning-of the units.

It was mentioned that operation of relays 55 and. 41 also operated the normally closed contacts 66 and 6! respectively. The operation of the said contacts prevents the grounded battery to be connected to any of the brushes 2ic, 22-0 and 23-0 as explained in conjunction with the coding or decoding operation so as to prevent faulty energization of magnet lit-5. Upon deenergization of the said relays 55 and .41 the contacts in the normally closed position permit the grounded battery 30 to be connected-to the saidbrushes to function as explained hereinbefore.

It has been'shown how the stepping or' displaced units may be returned to the normal position after either a completed coding or decoding function to permit subsequent similar function of the device.

It has also been shown that the displaceable contacts !2 are positioned at irregularly and arbitrarily timed intervals depending entirely upon the pattern of the connections of the described electrical circuits, thus effecting the sequence of the recorded characters on the secondary unit T-2 which is in accordance with the aperiodic changes of the connections of the interconnecting circuits from the primary unit Tl through contacts ll, segments I3-a, and

. movable contacts [2 to unit 'I'2.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the prior art and the scope of the following claims. a

What is claimed is:

1. A coding and decoding machine comprising a manually operable primary machine, a sec-= ondary machine operable from the first, coding means comprising a single movable circuit changcircuits, each adapted to be selectively closed by operation of the primary machine, means to position the coding means to transpose the said series of circuits interconnecting the machines, and a plurality of interconnected electrical control means under control of the primary machine to control the said positioning means at irregular 1 and arbitrary intervals, thereby altering the posiing device connecting the machines to control opondary machine operable from the first, coding means comprising a movable circuit changing device connecting the machines to control the" operation of the secondary machine from the primary machine including a series of electrical circuits, each adapted to be selectively closed by a operation of the primary machine, means to position the c ng means to transpose the said series of circuits interconnecting the machines, and a plurality of control circuits, at predetermined number of which are energized upon each operation of the primary machine, the remaining control circuits being controlled by the said predetermined number, all of the said control circuits interconnected to control the positioning means of the circuit changing device at irregular and arbitrary intervals.

' 3. A coding and decoding machine comprising a manually'operable primary machine,-a secondary machine operable from the first, coding means comprising a movable circuit changing device connecting the machines tocontrol the operation of the secondary machine from the primary machine including a series of electrical circuits, each adapted to be selectively closed by operation of the primary machine, means to position the coding means to transpose the said series of circuits interconnecting the machines, and a plurality of control units, a predetermined number of which are operated'at certain intervals during the operation of the said primary machine, the remaining control units adapted to be operated at other and. difierent intervals during the operation of the primary machine, all of the said control units interconnected to control the positioning means I circuits, each adapted to be selectively closed by operation of the primary machine, means to position'the coding means to transpose the said series of circuits interconnecting the machines, and a plurality of units comprising rotary switches controlled" by the primary machine to control the positioning means of the circuit changing device at irregular and arbitrary intervals.

5. A coding and decoding machine comprising a manually operable primary machine, a secondary machine operable from the first, coding means comprising a movable circuit changing de- .vice connecting the machines to control the operation of the secondary machine from the primary machine including a series of electrical circuits, each adapted to be selectively closed by operation. of the primary machine, means to position the coding means to transpose, the said series of circuits interconnecting the machines, and a plurality of electro-magnetic devices, a predetermined number of which are operated =upon each operation or the primary machine, the remaining electromagnetic devices adapted to be controlled by the said predetermined number, all of said devices interconnected to control the positioning means of the circuit changing device at irregular and arbitrary intervals.

primary machine including a series'of electrical- 6. The invention set forth in-claim 3 in which the said control units comprise relay devices with associated contacts which are arbitrarily interconnected so that upon each operation thereof the contacts complete circuit connections of varying pattern.

7. The invention set forth in claim 3 in which means are provided to reset the movable circuit changing device and'control units to a normal initial position whenever displaced therefrom by the operation of the positioning means.

8. A coding and decoding machine comprising a manually operable primary machine, a secondary machine operable from the first, coding means comprising a movable circuit changing device connecting the machines to control the operation of the secondary machine from the primary machine including a series of electrical circuits, each adapted to be selectively closed upon operation of the primary machine, means to position the coding means to transpose the said series of circuits interconnecting the machine's,

and a plurality of interconnected control circuits, and means to selectively energize at diiferent intervals the said control circuits to control the positioning means of the circuit changing device at irregular and arbitrary intervals.

9. A coding and decoding machine comprising a manually operable primary machine, a secondary machine operable from the first, coding means comprising a movable circuit changing de-' vice interconnecting the machines to control the operation of the secondary machine from the primary machine, including a series of electrical circuits, each adapted to be selectively closed by operation of the primary machine, means to position the coding means to transpose the said series of circuits interconnecting the machines, control means actuated upon each operation of the said primary machine, and additional control Ymeans associated with the first mentioned control means and controlled thereby, means to actuate at various intervals thsaid additional control means during the operation of the primary machine to control the said positioning means at irregular and arbitrary intervals.

WALTER S. LEMNION. CLYDE J. FITCH. RICHARD F. WALZ. 

